The present technology relates to a plate useful in mass spectroscopy such as matrix-assisted laser desorption ionization (MALDI) analysis and more particularly to a MALDI plate having a removable insert for supporting samples to be analyzed.
For the analysis of large molecules such as biomolecules, MALDI mass spectrometry has become a standard method. MALDI mass spectrometry has typically used expensive electrically conductive plates having high flatness tolerances to introduce chemical samples to the mass spectrometer (MS) instrument. This requirement for the plate surfaces to be extremely flat is due primarily to the need for the plate to become an integral part of the mass spectrometer to enhance signal resolution and mass accuracy of measurements made during the MALDI analysis. Current manufacturing practices prohibit making these plates cost effective enough to render them disposable. Therefore, the user is required to utilize laborious cleaning steps accompanied by the exercise of stringent quality control procedures to eliminate sample carryover from one analytical procedure to the next. Additionally, limited space in the ion source and the application of high voltage fields reduce the number of possible technology solutions for producing inexpensive single use plates. Archiving of sample plates containing precious samples for possible re-analysis also necessitates a relatively low cost plate. Furthermore, users are currently unable to cost effectively introduce into the MALDI MS special plate materials or surface chemistry for experimentation. For such experiments, it is common practice to attach trial materials such as membranes or tissue slices on top of current plates for analysis. This practice sometimes causes instrument instability and vacuum problems, and changes instrument optimization, rendering reproducible MS results far more difficult. Accordingly, it would be desirable to provide a sample plate for use in MALDI MS that is sufficiently cost effective to permit its use as a consumable. Such a sample plate would permit a onetime use of the plate thereby eliminating the need to clean the plate and the need for quality control checking of collected data Having a disposable plate thus ensures no carryover of analyte signals from a previous analysis for which the plate was used, while permitting multiple uses of a sample plate support structure.
In accordance with the present teachings, a MALDI sample plate structure is provided with a removable insert. The plate structure comprises a retainer plate having a central recess or xe2x80x9cpocketxe2x80x9d portion which is shaped to accept a sample plate insert which supports the analyte/matrix mixture. A portion or all of the bottom surface of the insert is formed of a magnetic material. The retainer plate is provided with a magnet suitable to provide sufficient force to retain the insert in the plate during MALDI MS analysis. In various embodiments the sample plate insert is configured to retain a plurality of samples and can be archived or discarded following a single use. In various embodiments, the sample plate can be coated with hydrophobic materials or uncoated. In various embodiments, the plate insert is disposable, and the retainer plate can be reused with additional sample plate inserts having different surface configurations, if desired.